Human papillomavirus (HPV) is a virus that a capsid surrounds double-stranded DNA of genome, and its shape resembles golf ball. HPV is important to human in terms of two viewpoints. Firstly, HPV is the most common sexually transmitted disease (STD). It is reported that 50% or more of all adult women is infected with HPV at least one during their whole life. Secondly, HPV is infected to the human epithelial cell, and induces hyperproliferation. Mostly, such hyperproliferation is a benign tumor such as simple skin wart, condyloma accuminata around external genital organ or anus and the like. However, HPV can be cause of inducing cancer, and actually nearly all cervical cancer, majority of head and neck tumor and numerous anal cancers are induced by HPV (Howley P M. Virology. Vol 2, 1996, 2045-2109; Murinoz N et al., N Engl J Med, 2003, 348:518-27).
HPV can be classified into following two types. One is a type that invades skin; the other is an anogenital type that invades boundary of skin and mucous membrane of external genital organ or anus. Depending on base sequence of genome, namely phylogenic tree or genotype), HPV can be classified specifically into approximately 120 types. Among them, 45 types of HPV including HPV 16 type (HPV-16), HPV-31, HPV-33, HPV-35, HPV-52, HPV-58, HPV-67, HPV-40, HPV-43, HPV-7, HPV-32, HPV-42, HPV-6, HPV-11, HPV-74, HPV-44, HPV-55, HPV-13, HPV-61, HPV-72, HPV-62, HPV-2, HPV-27, HPV-57, HPV-3, HPV-28, HPV-29, HPV-10, HPV-54, HPV-18, HPV-39, HPV-45, HPV-59, HPV-68, HPV-70, HPV-26, HPV-69, HPV-51, HPV-30, HPV-53, HPV-56, HPV-66, HPV-34, HPV-64  HPV-73 invade external genital organ and anus. Anogenital types of HPV can be classified into high-risk type and low-risk type and/or middle-risk type depending on ability to induce cervical cancer. High-risk type of HPV includes 22 types of HPV, that is HPV-16, HPV-18, HPV-26, HPV-30, HPV-31, HPV-33, HPV-35, HPV-39, HPV-45, HPV-51, HPV-52, HPV-53, HPV-56, HPV-57, HPV-58, HPV-59, HPV-61, HPV-67, HPV-68, HPV-70, HPV-73, And HPV-82. Among them, the most common high-risk type of HPV is HPV-16, and next is HPV-18, HPV-45, HPV-31, HPV-33, HPV-52 and HPV-58, although there is a difference in worldwide. Low-risk types of HPV includes approximately 20 types of HPV such as HPV-2a, HPV-3, HPV-6, HPV-10, HPV-11, HPV-32, HPV-34, HPV-40, HPV-42, HPV-43, HPV-44, HPV-54, HPV-55, HPV-61, HPV-66, HPV-69, HPV-70, HPV-72, HPV-81, and HPV-CP6108 (Murinoz N et al., N Engl J Med, 2003, 348:518-27).
Genome structure of HPV can be divided roughly into early transcription region E (early gene region), late transcription region L (late gene region), and non-expression region LCR (long control region). Genome structure of HPV affects outbreak type, risk and prognosis of HPV greatly. Particularly, E6 and E7 genes of the E region are integrated in the genome of infected cell, maintained and expressed, thereby played an important role to induce cancer. High-risk types of HPV such as HPV-16, HPV-18 and the like react with the most important tumor suppressor genes in human such as p53, E6AP, retinoblastoma (Rb, P105RB), P107, and P130 and the like and inactivate the tumor suppressor genes. As a result, the infected cell is transformed to cancer cell due to disorder of cell cycle regulation and apoptosis control mechanism. On the contrary, since low-risk types of HPV have low ability to react p53 or Rb tumor suppressor genes and inactivate the tumor suppressor genes, low-risk types of HPV is difficult to induce cervical cancer. Meanwhile, the largest gene of HPV genes is L1. L1 is present in similar preservative base sequence in most HPV types. L1 protein composes primarily of HPV capsid protein, and its antigenecity is the highest (Schneider A. Science 1993; 281:263-5; zur Hausen H. Semin Cancer Biol 1999; 9:405-11).
Once, cervical cell transformed by HPV is advanced to, so called, carcinoma in situ via precancerous lesion or dysplasia, cervical intraepithelial neoplasma (CIN), or squamous intraepithelial lesion (SIL). If the carcinoma in situ invades base layer under the epithelium cell, it becomes so called carcinoma or invasive carcinoma. 90% or more of HPV infected women removes HPV by means of immune system in body naturally. However, HPV is maintained in 10% of high-risk types of HPV infected women, and it induces cervical cancer. About 8% of precancerous lesions are advanced to carcinoma in situ, and about 20% of carcinoma in situ is developed to cancer. That is, in case that high-risk types of HPV in HPV infected patients are maintained for 10-20 years or more, the high-risk types of HPV induce cervical cancer, and the frequency is estimated to about 0.16%. Since the outbreak of cervical cancer is needed so long time period, and is induced by stages, it is possible to treat or prevent cervical cancer by early examining precancerous lesions in the middle stage of the outbreak. That is, it is possible to block carcinogenesis by removing precancerous lesions with preservative medical operation. Recently, the clinical test regarding vaccine against L1, the major antigen of HPV is in advancing. Also, an attempt to treat cervical precancerous lesions by using vaccines against E6 and E7 of HPV which are major causes inducing cervical cancer is advanced actively. However, for HPV vaccines, it is needed to prepare fixed vaccine by recognizing genotypes of each HPV (Bosch F X et al., J Clin Pathol, 2002, 55:244-65. Wallin K et al., N Engl J Med, 1999, 341:1633-8; Koutsky L A et al., N Engl J Med, 2002, 347: 1645-51).
Since it is very difficult to culture HPV and diagnose it in immunological examination or serum examination, the study regarding HPV is in stepping condition. However, with development of genetic examination method during past 20 years, an attempt to examine genotypes of HPV, thereby developing vaccines for diagnosis, prevention and treatment of HPV and screening cervical cancer using the results of the examination, is in advanced actively.
Particularly, the gene chip (or DNA chip or DNA microarray) was developed in recent by means of the combination of molecular biology and electronics, which can examine from tens to tens of thousands of genes on only one microscopic slide simultaneously. Such DNA chip is a new analytic system, which is applicable to analysis of gene expression, gene diagnosis, gene mutation diagnosis, drug screening and disease screening, and accurate diagnosis of bacteria and virus and the like. Accordingly, development of HPV DNA chip to detect rapidly and accurately high-risk types of HPV related to cervical cancer is attempted in worldwide.
Cervical screening is a conventional examination method used to screen primarily cervical cancer and prelesions thereof. Cervical screening is carried out by swabbing or scraping cervical cell with a tool of which a brush is attached to the tip of the tool, for example cotton stick, and then examining cytological type of the cell. Readout of the cervical screening is classified into normal, atypical squamous cell of unknown significance (ASCUS), low-risk type or low-grade squamous intraepithelial lesion (LSIL), high-risk type or high-grade squamous intraepithelial lesion (HSIL), carcinoma in situ or cancer. The cervical screening is also referred to papanicolou smear examination (Pap smear) according to the inventor. Pap smear examination has been used from 1940s and played an important role to reduce significantly mortality due to cervical cancer. However, Pap smear has disadvantage that false negative rate is high of 30-40%. Such high false negative rate is due to sampling error of sampler or readout error of inspector. Therefore, to avoid sampling error and reduce readout error, liquid based cytology examination, which is also referred to Thin Prep, is attempted in recent. Nevertheless, the false negative rate is still high. Accordingly, in recent ten years an attempt to recognize high-risk types of HPV and predict outbreak risk of cervical cancer by examining presence or absence of HPV infection and genotypes thereof has been accomplished. It is believed that HPV examination has higher screening accuracy than that of Pap smear.
It is recently reported that only one HPV examination can diagnose nearly all high-risk types of prelesions, and one HPV examination has higher accuracy than that of two Pap smear or colposcopic examinations. In addition, a combination of HPV examination and Pap smear can improve both screening sensitivity and specificity, since the combinational examination can solve the problems of Pap examination. Also, the combinational examination has an advantage that time interval of screening examination can be extended from 1 year (for only Pap smear) to 3-4 years. Accordingly, FDA recommends the combinational examination of Pap smear and HPV examination (Ledger W J et al., Am J Obstet Gynecol, 2000, 182: 860-5; Wright T C Jr et al., JAMA, 2001, 287:2120-9; Wright T C Jr et al., New Engl J Med, 2003, 348:6-7; Sherman M E et al., J Natl Cancer Inst, 2003, 95; 46-52).
Presently, examination of HPV genes can be divided into two methods. One is a method which examines presence or absence of HPV infection and rough type of HPV. The other is a genotyping method which examines presence or absence of HPV infection and rough type of HPV.
Former methods, namely representative methods which can diagnose HPV infection include PCR based method and hybridization based method. PCR based method is carried out by amplifying major virus capsid L1 gene of which its base sequence in genome of external genital organ type HPV is preserved most or E6 and E7 genes using consensus primer and confirming the results by means of electrophoresis and the like. However, this method can confirm only presence or absence of HPV infection, but cannot examine the genotype or even high-risk type or low-risk type of HPV which is presented. In addition, there are risks of false positive and contamination during the amplification. A representative hybridization based method is a hybrid II capture analytic method (Digene Diagnostics, Inc. USA). The hybrid capture method is carried our by extracting HPV DNA from specimen with hybrid capture technology, hybridizing the HPV DNA with high-risk HPV probe cocktail and low-risk HPV probe cocktail and diagnosing presence or absence of HPV infection. However, hybrid capture method has disadvantages that it is not possible to analyzing accurate genotype of HPV and lower sensitivity of examination due to no amplification. Similar method includes a method carrying out by PCR using consensus primer, hybridization with high-risk HPV probe cocktail and observation of enzyme immune response. This method is relatively simple and is useful for recognizing high-risk type of HPV, but cannot recognize low-risk types of HPV and accurate type of HPV (Kornegay J R et al., J Clin Microbiol, 2001, 39:3530-6).
The most standard method, which has been used to recognize presence or absence of HPV infection as well as genotypes thereof, is sequencing after PCR. The method is carried out by amplifying the region which base sequence is preserved in L1 gene and E6/E7 genes of external genital organ and base sequence is different depending on each type; and sequencing the base sequence directly or after cloning. The method is the most golden standard test. However, sequencing method has disadvantage that it can examine only one specimen by one or two examination; a plenty of time and cost are needed; it is labor-intensive. Accordingly, it is difficult to apply the sequencing method to clinical test. Also, although cloning is necessary to recognize complex infection of at least one types of HPV, actually such procedures are impossible. Accordingly, following methods are attempted in place of sequencing method.
First method is a method carrying out several PCR using genotype specific primer according to each HPV types. This method is to recognize various sizes of PCR products by means of electrophoresis or southern blotting for each HPV genotypes. The method is simple, but labor-intensive and inefficient. Also, the method has disadvantage that it can recognize minority of HPV types.
Second method is restriction fragment length polymorphism after PCR (PCR-RFLP). This method is carried out by amplifying L1 gene or E6 and E7 genes with PCR using consensus primer; digesting the PCR products with restriction enzyme; and determining the length of the products by means of electrophoresis. The method is conventional and labor-intensive. Also, the method has disadvantage that it can recognize minority of HPV types (Vermon S D et al. J Clin Microbiol, 2000, 38:651-5).
Third method is a reverse hybridization line blot detection method, which is used during recent 6-7 years. The method is carried out by preparing nylon membrane strip which genotype specific oligonucleotide probes for each types of HPV are attached thereon; positioning the consensus primer PCR products of HPV; and determining the types exhibiting the strongest response by hybridization. The method is used in the name of PGMY-line blot assay or SFP10 line probe assay and the like (Gravitt P E et al., J Clin Microbiol, 1998, 36:3020-7; van Doorn L et al., J Clin Microbiol, 2002, 40:979-983). It is reported that these methods can recognize 25-27 types of HPV in maximum. However, these methods are labor-intensive, difficult to be automated, and cannot recognize all genotypes of HPV. In addition, since target region for determination is localized to 50 bases in certain region of L1 gene, PCR amplification cannot be carried out efficiently due to intragenic variations. Also, the method has disadvantages that to recognize gene variants is difficult, and it can not recognize E6 and E7 genes which played a conclusive role to induce cervical cancer.
Finally, recently, oligonucleotide microarray or DNA chip has been developed and used. The DNA chip uses procedures of the reverse hybridization method above, except that microscopic glass slide is used in place of nylon membrane strip (Cho N H et al. Am J Obstet Gynecol, 2003, 188:56-62). The DNA chip can be automated readily compared to reverse hybridization method above. However, the DNA chip has same disadvantages as those of the reverse hybridization method. That is, the DNA chip can not recognize all genotypes of external genital organ HPV, and can recognize only 22 types; since target region for determination is localized to 50 bases in certain region of L1 gene, PCR amplification can not be carried out efficiently; to recognize gene variants is difficult; and it can not analyze E6 and E7 genes.
Conditions that are demanded in reasonable HPV genotype examination method are as follows:                (1) It has to be able to diagnose all types of HPV including complex infection of external genital organ HPV;        (2) All of sensitivity, specificity and reproducibility should be closed to 100%;        (3) It has to be able to analyze L1 gene as well as E6 and E7 genes;        (4) It has to be able to analyze wild type base sequence and mutant base sequence of the genes;        (5) Examination procedures and analysis of the examination results should be simple;        (6) It should be automated to analyze a multiplicity of specimens in short time.        
As a result, DNA chip is suitable. However, to date, no DNA chip has been commercialized which satisfies the conditions above. Considering the regional characteristics, it is necessary to produce DNA chips based on the database built by obtaining cervical cell specimens from many Korean women; recognizing genotypes and variation of HPV that is present in the cervical cell specimen.